Retrievable well packer



Sept. 16, 1969 J. w. KISLING m 3,467,182

RETRIEVABLE WELL PACKER Filed Feb. 8, 1968 4 Sheets-Sheet 1 JAMES W.KISLING 111 FIG. /8

FIG. m hi; ATTORNEYS J. w. KISLING Ill RETRIEVABLE WELL PACKER Sept. 16,1969 4 Sheets-Sheet 2 Filed Feb. 8. 1968 w w m a M IN VI LIN"! Y 1RJAMES W. K'SLING m his ATTORNEYS 4 4 m 4 2 2 8 48 6 I 6 kA 1 1 3 z 4 wfl Q \N M'Wl i; 0 w. 7 a IO P 1969 J. w. KISLING m 3,47,12

REIRI EVABLE WELL PACKER Filed Feb. 8, 1968 4 Sheets-Sheet 5 hisATTORNEYS United States Patent 3,467,182 RETRIEVABLE WELL PACKER JamesW. Kisling III, Houston, Tex., assignor to Schlumberger TechnologyCorporation, Houston, Tex., a corporation of Texas Filed Feb. 8, 1968,Ser. No. 703,947 Int. Cl. E21h 33/129, 23/06 US. Cl. 166-121 24 ClaimsABSTRACT OF THE DISCLOSURE A well tool, according to the exemplaryembodiments, is of a type adapted to be anchored in a well conduitagainst both upward and downward movement and comprises a body, packingelements for packing on the annulus and an anchoring structure in theform of a single expander and a set of coacting slips mounted formovement toward and away from each other and longitudinally of the bodybetween limit positions. The expander and slips are both equipped withfriction drag blocks which engage the conduit wall and impede theirmovement through the well. Upon a fluid pressure condition which tendsto move the well tool body in a direction to move the expander relativeto the slips and expand the slips, the friction drag associated with theslips precludes movement of the slips and aifords relative movementbetween the expander and slips to engage the slips in anchoringengagement with the well bore wall. Under pressure conditions tending tomove the tool in the opposite direction, namely, to move the slips, theexpander is forced toward the slips by differential pressure acting on afluid chamber of variable volume, one wall formation of which is anelement on the expander and constitutes a moving wall of the chamber.Accordingly, differential pressure between the inside and outside of thechamber causes the expander to be moved toward and under the slips towedge the slips into gripping engagement with the well bore wall. Thetool further includes a control mechanism for maintaing the slips andexpander in inactivated condition when the tool is run into or retrievedfrom the well and for releasing the expander from engagement with theslips to release the tool for movement in the well.

Background of the invention This invention relates to a well tool of thetype that is adapted to be lowered into a well conduit, anchored in thewell conduit against both upward and downward movement, released fromand moved in the conduit and ultimately retrieved.

In many operations performed in a well, such as fracturing, acidizing,squeeze cemeting, testing and other remedial, stimulation and productionoperations, various forms of well tools of the type that can be anchoredto a well conduit are employed. For example, certain operations employ alower tool, commonly known as a bridge plug, to seal or pack off fullythe entire cross-section of the well or an upper tool or so-called wellpacker to isolate an annular space between the casing and a tubingstring comunicating the well surface with a zone below the packer fromthe remainder of the well, or both of these tools. Various forms ofbridge plugs and packers ice having been proposed and used for theseoperations. Many of the tools are of the so-called retrievable typewhich are capable of being lowered into the well bore, manipulated toanchor them to the well casing or other well conduit, released afteruse, and moved to another location or retrieved from the well.

The anchoring mechanisms used in some retrievable tools of the type thatare anchored to the well bore in a manner which precludes movement ofthe tool in either direction employ two sets of slips, each of which isassociated with an expander. In one form of such tools, the expandersare spaced from each other and are tapered inwardly toward each other,the slips being located between the expanders and the spacing betweenthe expanders being sufiicient to afford movement of the slips relativeto the expanders. The upper expander and upper set of slips coact toanchor the tool against downward movement, while the lower expander andlower set of slips coact to anchor the tool against upward movement inthe well bore. Associated with the two sets of slips are friction dragelements that engage the well bore wall and impede the movement of theslips relative to the expanders, and an appropriate control mechanism isprovided to either maintain the slips in a de-activated positionrelative to the two expanders or to permit movement of the slipsrelative to the expanders so that the tool may become anchored in thewell. The tools of this type involve selective operation of the slips,only one set of slips being engaged at any given time, depending uponwhether the tool is anchored against downward movement or upwardmovement.

In many operations the pressure diiferential across the tool may shiftand thereby require that one set of slips and the expander associatedwith that set be released from anchoring engagement with the well borewall and the other set of slips and the associated expander be engagedto anchor the tool against movement in the other direction. The shiftingof the anchoring function from one set of slips to the other requiresthe tool body to move longitudinally in the well bore and also involves,in the course of shifting, a stage or period at which neither set ofslips is anchored to the well bore Wall and in which opportunity formovement of the entire tool a substantial distance up or down the wellis afforded. In many instances it is important that the tool be locatedand remain relatively precisely at a predetermined level in the well,and movement of the well tool upon a change in pressure conditions canhave serious consequences.

Summary of the invention There is provided, in accordance with theinvention, a retrievable well tool which includes an anchoring structureof the type adapted to anchor the tool against both upward and downwardmovement in the well, the anchoring mechanism having but one set ofslips and an expander which coact to anchor the tool against both upwardand downward movement and remain set in anchored engagement regardlessof a shift in pressure conditions that changes the direction in whichthe slips are holding. The expander and slips are both mounted formovement longitudinally on a tool body which includes abutments thatengage the expander and slips and limits the extent of their movementaway from each other as well as transmit forces and motion from the bodyto them. The abutments are located so that the expander and slips are ininactive relation, with the slips withdrawn from engagement with thewell conduit, when each is engaged with the slips or expander,respectively.

The tool further includes packing elements, preferably of the cup-typewhich engage and seal the annulus between the tool and conduit.Associated with the expander and the slips are friction drags, such asspring-loaded friction drag blocks, which engage the well bore wall andimpede the movement of the expander and slip structure, respectively,through the well bore. A control mechanism maintains the slips andexpander in inactive positions when the tool is being run into, movedin, or retrieved from the well, and is operable to permit movementbetween the expander and slips toward each other so that the slips areexpanded outwardly into gripping engagement with the well bore wall. Thecontrol mechanism is, desirably, operably solely by longitudinalmovements, so that the tool can be used with a wire line, as well aswith tubing, and comprises a control element which selectively (a)prevents movement of the expander relative to the body, (b) preventsmovement of the slips relative to the body, or (c) permits the slips,expander and body to move relative to each other so that the slips canbecome anchored to the conduit.

Upon movement of the tool body in a direction to cause the expander tobe engaged by the body and moved relative to the slips, the slips areimpeded from moving in the well bore with the body by the friction dragelements associated with them, thereby afiording relative movementbetween the expander and the slips so that the slips are forcedoutwardly into anchoring engagement with the casing. Movement of thebody in the other direction so that the abutment associated with theslips engages the slips and causes them to move toward the expandersimilarly moves the slips into gripping engagement with the well borewall, the expander being impeded from moving with the body and slips bythe friction drag elements associated with it. However, even when theslips engage the well bore wall, the expander is relatively free to moveinasmuch as the only impediment to its movement is provided by thefriction drag elements. Accordingly, an important element of theinvention is the provision of a fluid pressure system for urging theexpander toward the slips when the body tends to move in a directionurging the slips toward the expander. In other words, the well toolincludes a fluid pressure arrangement by which the expander is forcedunder the slips to engage them more firmly with the well bore wall whenthe body of the tool is subjected to the forces tending to move it in adirection counter to the taper of the expander surfaces. I

More particularly, the fluid pressure arrangement comprises a fluidchamber of variable volume defined by formations on the body and on theexpander, a part of the formation on the expander constituting a movingwall of the chamber. The interior of the chamber communicates with oneof the pressure zones in the well bore on one side of the packing, whilethe exterior of the chamber communicates with the pressurezone on theother side of the packing.

The anchoring mechanism in the well tool according to the invention hasthe important advantage over similar types of tools of providingengagement of the single set of slipsor equivalent anchoring elementswith the well casing, regardless of the direction of forces tending tomove the tool in the conduit. Accordingly there is no shifting of thepoint where the tool is anchored to the well conduit wall. Moreover, theslips remain in engagement with the conduit throughout any stage inwhich the tool is not subjected to any forces tending to move it, suchas the nul stage occurring when the pressure conditions in the well arechanging from a higher pressure 4 above the tool to a higher pressurebelow the tool. Accordingly, the opportunity for the tool to move anysubstantial distance in the well bore, beyond the relatively smallshifting movement of the body relative to the anchoring structure, issharply reduced. The inclusion of only one expander and one set of slipsin the well tool of the invention also reduces the number of parts, thecomplexity of the construction, and the costs of manufacture, assemblyand maintenance.

Another advantage of tools constructed according to the invention istheir capability of being used with a wire line, i.e., cable, as well aswith tubing. In some operations, a tubing string is not needed, andsince running tubing is considerably more time-consuming and costly thanrunning wire line, considerable savings are aflForded by a wire linetool.

Description of the drawings For a better understanding of the invention,reference may be made to the following description of an exemplaryembodiment, taken in conjunction with the figures of the accompanyingdrawings, in which:

FIGS. 1A and 1B, taken together end-to-end in that order, make up ahalf-sectional, half-elevationa1 side view of the tool, the tool beingshown in its configuration when it is being moved downwardly through thewell conduit;

FIGS. 2A and 2B, taken together end-to-end in that order, make up ahalf-elevational, half-sectional side view of the tool, showing itanchored against downward movement in the well conduit;

FIG. 3 is a half-elevational, half-sectional side view of the majorportion of the tool, showing it anchored against upward movement in theconduit; and

FIGS. 4A and 4B, taken together end-to-end in that order, make up ahalf-elevational, half-sectional side view of the tool in itsconfiguration when it is being moved upwardly through the conduit.

Description of exemplary embodiment The embodiment of the well toolillustrated in the drawings and described below is a retrievable bridgeplug ofthe type that can be lowered into a well conduit using a suitablecoupling tool, released from the coupling tool ata desired location,and, upon any pressure differential in the well, anchors to the conduitwall against movement in eitherdirection and seals off the conduitagainst the passage of well fluids in either direction across the tool.

The retrievable bridge plug, in the form illustrated in the drawings, isdesigned for use in a cased well, a portion of the well casing beingillustrated in the drawings and being designated generally by thereference numeral 10, but a similar tool can be used in other wellconduits, such as tubing. The retrievable bridge plug includes anelongated body 12, which will generally be made up of a number ofsections joined together by threaded or other appropriate forms ofconnections. For simplification, the several sections making up the body12 are not depicted in the drawing. A central bore 14 extendssubstantially the entire length of the body 12 and is communicated by aseries of circumferentially spaced ports 16 formed in a head section 18of the body with the portion of the casing above the tool and iscommunicated through similar ports 20 in a bottom section 22 of the bodywith the part of the casing below the tool. A major length-wise part ofthe bore 14 is defined by the internal lsjuiface of a sleeve 23, thepurpose of which is described e ow.

Adjacent the upper end of the housing bore 14 are two valve housingcavities 24 and 26, each of which contains a spring-loaded bypass valveelement 28 and 30, respectively. The upper valve 2-8 is urged downwardlyby a spring 32 into engagement with a seat 34 formed on the body, whilethe lower valve 30 is urged upwardly by a spring 36 into engagement witha seat 38. In FIGS. 1A

and 1B, the valves are shown in their open positions in which theyafford the passage of well fluids from below the tool through the ports20, upwardly through the central bore 14, past the valves 28 and 30 andout into the zone of the well above the tool through the ports 16. Asdescribed below, the bypass valves are kept open as the tool is moveddownwardly or upwardly in the conduit, but are forced closed by thesprings 32 and 36 when the tool is released from the coupling tool usedto move it in the conduit.

Mounted near the upper end of the body, just below the valve cavities 24and 26, are two cup-type packer elements, specifically an upper packerelement 40 which is constructed and is mounted on the tool such that itstops fluid passage through the annulus between the tool and casing in adownward direction, i.e., holds pressure from above, and a lower packerelement 42 which holds pressure from below. The packer elements 40 and42 may be of any appropriate specific design, many of which are wellknown to those skilled in the art, and therefore the details of theirconstruction and installation on the tool need not be described here. Itsuffices to say that a portion of the outer perimeter of each of thepacker elements 40 or 42 engages the inner surface of the well casingand is sealed to the tool body in a manner forming a seal against thepassage of fluids through the annulus in a direction against the concaveside of the cup part.

At the lower end of the tool (FIG. 1B, for example) is an anchoringstructure which is composed of an expander member, designated generallyby the reference numeral 44, and a series of circumferentiallyspacedapart slips 46 forming a part of a slip structure, designatedgenerally by the reference numeral 48. The expander member 44 includesdownwardly and inwardly tapering expander surfaces 50 at its lower end,one such surface for each slip 46, and a sleeve portion 52 extendingupwardly from the expander surface portion. A series ofcircumferentially spaced-apart friction drag shoes or blocks 54, each ofwhich is urged outwardly into engagement with the casing by springs 56,is carried by the sleeve portion 52. The expander member 44 is mountedfor longitudinal movement on the body 12, but the upward movement of theexpander member relative to the body is limited by an abutment 58 on thebody which engages the upper end of the sleeve portion 52 and abutmentsor shoulder formations (e.g., 60) on the body in the region radiallyinwardly of the expander surface portion 50.

The slip structure 48 includes the slips 46, a housing or mountingmember 62 which is slidable on the body and a series of spring-loadedfriction drag blocks 64. In the embodiment illustrated in the drawings,the slips 46 are of the type which dove-tail with the expanders byappropriate rib and groove formations on the slips and the expander, andthey are linked to the mounting member 62 by links or so-called reins66. The extent of downward movement of the slip structure 48 on the bodyis limited by an abutment 68 on the body which engages the lower end ofthe slip mounting member 62.

The abutments 58 and 60 associated with the expander and the abutment 68associated with the slip structure 48 are spaced widely enough apart sothat the slips remain retracted inwardly from the well casing, by virtueof the slips being relatively widely separated longitudinally from theexpander, when the expander and slip structures engage the respectiveabutments.

The retrievable bridge plug is controlled by a control mechanism whichincludes a control mandrel 70 extending from above the top of the body12 down through the central bore 14 through the tool body to a pointnear the bottom of the body. At the upper end of the control mandrel 70is a fitting 72 which is complementary to and coacts with a releasablecoupling device (not shown) by which the tool is moved through the well.The coupling device may be of various types, such as a suitable I-slotcoupling, and may be of the type that is used with either a wire line(cable) or a tubing string by which the tool is run into, manipulated inand removed from the well.

Between the two valve elements 28 and 30 (which, it should be mentioned,are ring-like members surrounding and sealed to the mandrel) is a flange74, and at the lower end of the mandrel 70 is an elongated slot 76 whichreceives a cross-piece 78 that extends across the bore 14 and protrudesout through elongated slots 80 formed in the body. The mandrel 70 isshiftable longitudinally of the body to the extent afforded by the lostmotion available by virtue of the slot 76 in the mandrel and the slots80 in the body.

The tool is moved downwardly in the well by pushing down on the controlmandrel 70, through the medium of the coupling tool and pipe, or byweights associated with the coupling tool when wire line is used. Adownward force on the mandrel 70 causes it to seek its lowermostposition relative to the tool body, thereby, as shown in FIGS. 1A and1B, causing the mandrel 70 to engage the upper edge of the cross-piece78 and in turn causing the lower edges of the cross-piece 78 to engagethe lower edges of the slots 80 in the tool body. In the meantime, theflange 74 at the upper end of the mandrel engages the top of the lowerbypass valve element 30, thus unseating it and permitting well fluids topass upwardly through the bore 14 in the body. The pressure of the fluidcreated as the tool moves down forces the upper valve element 28 to openagainst its spring 32 and bypass the fluid through the bore and outthrough the ports 16.

The downward force on the control mandrel 78 is transmitted to the toolbody 12 through the cross-piece 78 by engagement of the lower edges atthe extreme ends of the cross bar 78 with the upper edges of the slipmounting member 62 (see FIG. 1B) which in turn acts through the abutment68; the slip structure 68 is therefore pushed by the cross-piece to itslowermost position on the tool with the lower end of the housing 62 inengagement with the abutment 68 on the tool body. The tool body may alsobe pushed down through the casing by direct engagement of the lower endof the coupling tool with the top end of the body.

The body 12 resists downward movement by virtue of the frictionalengagement between the friction drag elements 54 on the expanderstructure 44 with the well bore casing, thereby causing the expanderstructure to assume a supporting position for the body by engagement ofits upper end with the abutment 58 on the body and at the same timemaintaining itself separated from the slips. In addition, the packingelements 40 and 42 provide additional support for the tool againstdownward movement into the well. Consequently, the tool supports itselfin the casing and must be pushed down. The configuration of the toolwhen it is being moved downwardly in the casing is illustrated in FIGS.1A and 1B.

When the desired location at which the retreivable bridge plug is to beset has been reached, the coupling tool is detached from the fitting 72at the upper end of the control mandrel 70 or, at least, the controlmandrel is otherwise appropriately released from downward force. Whenthis occurs, the spring 36 acting through the valve elements 30 on theflange 74 of the control mandrel 70 pushes the mandrel upwardly relativeto the body and at the same time causes the lower valve 30 to engage thelower valve seat 38. Accordingly, the upward passage of well fluidsthrough the tool bore 14 is terminated. The upper valve 28 is also urgedclosed by its spring 32 into seating engagement on the upper valve seat34. In conjunction with the sealing action of the packer elements 40 and42, the closing of the bypass valves 28 and 30 blocks the passage ofwell fluids in either direction between the portions of the well aboveand below the bridge plug, in other Words, bridges the casing.

Upon movement of the control mandrel 70 upwardly relative to the body,as described in the preceding paragraph, the slot 76 at its lower endassumes a position generally aligned with the slots 80 in the body sothat the cross-piece 78 is freely movable through the two slots 76 and80. In other words, the control mandrel 70 has assumed a neutralposition relative to the tool body. Because the cross-piece 78 is freelymovable, movement of the expander and slip structure relative. towardeach other can take place at any time that a force on the tool body ineither direction exceeds the resisting force of the friction drag blocks54 or 64 plus other forces, such as the frictional forces of the packerelements, which are then resisting the movement.

More particularly, inasmuch as the tool new constitutes an obstructionor bridge against the passage of well fluids in either direction acrossit, it acts as a piston in the casing and responds to the existence ofany forces due to a differential between the pressures of the wellfluids in the casing above and below the tool by tending to moveupwardly or downwardly toward the lower pressure zone. For example, if ahigher pressure is created in the zone of the well above the tool, suchas by pumping fluids down the casing or a tubing string, thedifferential pressure may and usually does (depending on the magnitudeof the differential) create a net downward force on the tool tending tomove it downwardly through the casing. The downward movement of the toolbody in this instance causes the abutment 58 to engage the upper end ofthe expander structure 44 and pushes the expander down. Meanwhile, theslip structure 48 is supported against downward movement in the otherparts of the tool by frictional engagement of the drag blocks 64 withthe casing wall. Consequently, the expander structure 44 is shifteddownwardly relative to the slip structure 48, thereby causing relativesliding movement between the tapered surfaces of the slips.Consequently, the slips are forced outwardly into anchoring engagementwith the well casing. After the relatively small downward shifting ofthe tool required to wedge the slips outwardly so that they grip andhold the casing, the tool is precluded from moving further down theeasing and is anchored against downward movement. The configuration ofthe tool when it is anchored against downward movement, in other wordswhen it is anchored and sealed against a higher pressure in fluids abovethe tool than below, is illustrated in FIGS. 2A and 2B.

Starting again with the retrievable bridge plug in the neutral positiondescribed above, that is, referring back to the point at which the toolwas initially uncoupled from the coupling device and the control mandrel70 assumed a neutral position, the creation of a higher pressure belowthe tool than above, such as higher pressure created by a producingformation below the tool or by swabbing the casing above, similarlyresults in anchoring the tool against movement in the well, in this caseagainst upward movement (see FIG. 3). The differential pressure acrossthe tool creates forces on the tool body tending to move it upwardlythrough the well the piston effect), thus engaging the abutment 68adjacent the lower end of the tool body 12 with the lower end of theslip structure mounting sleeve 62 and pushing the slip structure 48upwardly with the body. Meanwhile, the friction drag blocks 54 on theexpander member 44 keeps the expander member from moving up with theremaining parts of the tool, thereby affording relative movement of theslips upwardly along the expander surface 50 and consequently causingthem to be forced outwardly into engagement with the well casing. Whenthe slips engage the well casing, their upward movement with the tool issomewhat restricted; however, the structure as described thus farprovides resistance against upward movement of the expander with theslips only by the friction forces of the expander drag blocks 56. Inthis regard, once the slips engage the casing wall, their further upwardmovement is impeded, not by firmly biting into the casing by wedgingaction but by relatively light outward force at this point. Firmanchoring engagement is not certain to occur, and the slips and expandermay drag up along the casing wall. This problem does not arise when theexpander is pushed down under the slips, as in the normal settingagainst pressure from above the tool, or as provided for in the furtherstructural and functional features of the tool described below.

A downward force on the expander toward the slips is provided by a fluidpressure arrangement, thereby wedging the slips out into firm anchoringengagement with the casing. The fluid pressure system includes aninternal bore 82 on the expander sleeve which is in sliding relation toand is sealed by an O-ring 83 with a flange forma tion 84 on the body.The bore 82 defines in part, a fluid chamber 85 which is further definedby the end face 86 of the flange 84, a face 88 at the upper end of thebore 82 and the part 89 of the outer wall of the tool body 12 facing theinner surface of the bore 82. The interior of the fluid chamber 85communicates with the portion of the casing above the upper packer 40through an annular passageway '90 defined by the internal surface of thebody 12 and the sleeve 23 (referred to above) installed within the body.A series of circumferentially spaced-apart holes 94 through the body 12near the lower end of the passageway and similar holes 96 through theupper end of the passageway communicate the passageway with the fluidchamber 85 and with the upper part of the well above the packer,respectively. Consequently, the interior of the chamber is atsubstantially the same fluid pressure as the zone of the well above thepackers.

(It may be mentioned at this point that the passageway 90 may takevarious forms, such as a series of longitudinal holes formed in the bodyand moreover that the upper end of the passage may communicate with thespace between the two packer elements 40 and 42, inasmuch as the annularspace between the packer cups 40 and 42 tends to be at substantially thesame pressure as that zone of the well above or below the tool which isat the lower pressure.)

Inasmuch as the two packer elements 40 and 42 are located above thefluid chamber 85, the well fluids surrounding the chamber are at thehigher pressure of the zone below the packer elements. Accordingly,there is a differential pressure existing between the interior andexterior of the chamber 85 which creates a net force downwardly on theexpander structure 44, the pressure difference acting on the upper endof the expander sleeve which constitutes a moving wall or piston. As thedifferential pressure across the tool increases, the pressuredifferential between the interior and exterior of the fluid chamber85.similarly increases, thereby increasing the magnitude of the downwardforce of the expander structure 44 and more firmly forcing the expanderdownwardly along the slips so that the slips are correspondingly moretightly wedged against the casing in gripping engagement. Therefore, thetool is firmly anchored against upward movement in the well bore.

Assuming that the tool is anchored against movement in one direction,say against downward movement as depicted in FIGS. 2A and 2B, a shift inthe pressure conditions so that the higher pressure shifts from abovethe tool to below the tool tends to shift the body upwardly. Before thechange in pressure conditions, the slips are firmly engaged with thewell casing, and as the pressure difference shifts, the expander andslips remain engaged and act essentially as a unit on the tool which isanchored to the wall casing. The slight movement of the tool body thatoccurs can take place relatively freely, inasmuch as it is impeded onlyby the frictional engagement between the packer elements and the casing(plus the weight of the tool). Accordingly, the body of the tool shiftsrelative to the anchoring structures from the position illustrated inFIGS. 2A and 2B into the position illustrated in FIG. 3. Just as in thecase when the tool initially sets against higher pressure *from below,the creation of a higher pressure outside of the fluid chamber 83 thanthe pressure inside the chamber creates a downward force on the expanderand keeps the slips firmly engaged.

The reverse of the situation described in the preceding paragraph occurswhen the tool is initially anchored against upward movement against ahigher well fluid pressure below the tool and the higher pressure shiftsto the zone above the tool. Beginning with the tool in the configurationillustrated in FIG. 3, a higher pressure above the tool causes the bodyto move downwardly, such shifting being relatively free as describedabove, thereby shifting the body so that the upper abutment 58 on thebody engages the expander structure 44 and transmits the forces due todifferential pressure through the expander and into the slips to wedgethem firmly into anchoring engagement with the casing. With the shift inpressure, the fluid pressure inside the fluid chamber 85 is higher thanthe pressure outside so that the eifect of pressure conditions on thefluid chamber 85 are such that the expander structure 44 is forcedupwardly relative to the body. Actually, this condition is inherentlyproduced by the downward movement of the body which engages the abutment58 with the expander structure, and the pressure conditions obtaining inthe fluid pressure arrangement are of minor consequence.

After the completion of operations employing the retrievable bridge plugat a given location in the well conduit, the bridge plug can be releasedand moved to another location for further operations or can be retrievedfrom the well bore. To release the bridge plug, the coupling tool (notshown) is lowered and reconnected to the fitting 72 at the upper end ofthe control mandrel 70. To ensure that the pressures below and above thetool are substantially equalized, the coupling tool is lowered tocorrespondingly push down on the control mandrel 70 so that the flange74 engages the lower valve element 30 and pushes it against the springto unseat it and permit any higher pressure below the tool to equalize.The coupling is then raised to correspondingly pull up on the controlmandrel, the upward movement of the control mandrel 70 engaging theflange 74 with the upper valve element 28 and unseating it to allow ahigher pressure above the tool to equalize with the pressure below it.

The bridge plug is released by pulling the control mandrel 70 up. Thisbrings the lower end of the slot 76 at the lower end of the mandrel intoengagement with the lower edge of the cross-piece 78 and moves thecrosspiece 78 upwardly so that its upper edge engages (1) the upper edgeof the slot 80 in the body and (2) the lower end of the expanderstructure 44. With further upward movement, the expander and body arepulled upwardly relative to the slips, thereby withdrawing them fromgripping engagement with the casing and releasing the bridge plug fromanchored position in the well casing. At this point, the bridge plug isin the configuration depicted in FIGS. 4A and 4B.

The bridge plug can now be moved upwardly in the casing in theconfiguration illustrated in FIGS. 4A and 4B, the upward pull on thecontrol bar 70 engaging the cross-piece 78 with the upper edge of theslot 80 and the lower edge of the expander structure moving them as aunit while the slip assembly 48 remains in a relatively downwardposition on the tool body by virtue of its weight and the frictionforces developed by the drag blocks 64. The lower end of the slipmounting sleeve 62 is engaged and pushed upwardly by the abutment 68.The upper bypass valve 28 is held open by the shoulder 74 on the controlbar so that well fluids above the tool can pass downwardly through thebypass passage 14 through the tool and downand out through the lowerports 20.

On the other hand downward movement of the tool can be accomplished inthe manner described above with the tool in the configurationillustrated in FIGS. 1A and 1B. Should it be desired to employ thebridge plug at another location in the well, it can be released from thecoupling tool and reset in the casing in precisely the manner that hasbeen previously described.

The above-described embodiment of the invention is intended to be merelyexemplary, and those skilled in the art will be able to make numerousvariations and modifications of it without departing from the spirit andscope of the invention. All such variations and modifications areintended to be included within the scope of the invention as defined inthe appended claims.

I claim:

1. A well tool comprising a body adapted to be lowered into a wellconduit, cup-type packing means on the body engaging the conduit to sealthe annular space between the tool and the well conduit against passageof well fluids in either direction therethrough between zones above andbelow the tool, slip means mounted on the body for shifting movementthereon longitudinally outwardly into anchoring engagement with the"well conduit, an expander mounted for longitudinal movement relative tothe body and to the slip means to urge the slip means into anchoringengagement with the conduit, fluid pressure means coupled to theexpander and responsive to differential pressure between the said zonesfor forcing the expander toward the slip means to urge the slip meansinto anchoring engagement with the well conduit, and control means forselectively preventing or permitting relative movement of the body,expander and slip means.

2. A well tool according to claim 1 further comprising a passage throughthe body communicating the parts of the well bore above and below thepacking means with each other, and valve means in the passage andoperable by the control means to selectively close ofi? the passage toprevent communication of well fluids between the said zones.

3. A well tool according to claim 1 wherein the con trol means includesfriction drag means associated with the slip means and engageable withthe Well conduit to impede movement of the slip means through theconduit, and friction drag means associated with the expander to impedemovement of the expander through the conduit.

4. A well tool according to claim 1 wherein the fluid pressure meansincludes a fluid chamber of variable volume defined by formationsassociated with the body and the expander.

5. A well tool according to claim 4 wherein the formations associatedwith the expander include a wall formation movable with the expanderconstituting a moving wall of the fluid chamber.

6. A well tool according to claim 4 wherein the interior of the chambercommunicates with one of said zones of the well and the exterior of thechamber communicates with the other of said zones.

7. A well tool according to claim 1 wherein the control means includesmeans for selectively (a) preventing movement of the slip means relativeto the body, (b) preventing movement of the expander relative to thebody, or (c) enabling relative movement between the body, slip means andexpander to permit the expander to urge the slip means into anchoringengagement with the well conduit.

8. A well tool according to claim 7 wherein the control means includes amember shiftable longitudinally of the body and elements coupled to themember and selectively engageable in different positions of the memberrelative to the body with the body, expander, and slip means to maintainthe body, expander and slip mean in selected positions relative to eachother.

9. A well tool according to claim 8 wherein the elements include acoupling member carried by the longitudinally shiftable member forrelative longitudinal movement thereon between limit positions andhaving portions 1 1 selectively engageable with the body, expander andslip means.

10. A well tool comprising a body adapted to be lowered into a wellconduit, packing means on the body for sealing the annular space betweenthe body and the well conduit against passage of well fluids in eitherdirection therethrough between zones above and below the tool, anexpander mounted on the body for movement longitudinally of the body, anabutment on the body engageable with the expander to restrict the extentof movement of the expander relative to the body, slip means mounted onthe body for movement longitudinally of the body and relatively alongthe expander thereby selectively to be urged outwardly into engagementwith the well conduit, a second abutment on the body engageable with theslip means to restrict the extent of movement of the slip means relativeto the body, friction drag means associated with the expander andengageable with the well conduit to impede movement of the expanderthrough the conduit, friction drag means associated with the slip meansand engageable with the well conduit to impede movement of the slipmeans through the conduit, fluid pressure means coacting between thebody and expander and responsive to a differential pressure between thesaid zone to force the expander toward the slip means to urge the slipmeans in to anchoring engagement with the well conduit, and controlmeans for selectively (a) preventing movement of the slip means relativeto the body, (b) preventing movement of the expander relative to thebody, or (c) enabling relative movement between the body, slip means andexpander to permit the expander to urge the slip means into anchoringengagement with the well conduit.

11. A well tool according to claim further comprising a passage throughthe body and communicating the parts of the well bore above and belowthe packing means with each other, and valve means in the passage forselectively closing off the passage to prevent communication of wellfluids between the said parts.

12. A well tool according to claim 11 wherein the valve means is coupledto and operated by the control means.

13. A well tool according to claim 10 wherein the fluid pressure meansincludes a fluid chamber of variable volume defined by formationsassociated with the body and the expander.

14. A well tool according to claim 13 wherein a formation associatedwith the expander constitutes a moving wall of the fluid chamber.

15. A well tool according to claim 13 wherein the interior of thechamber communicates with one of the said zones and the exterior of thechamber communicates with the other of said zones.

16. A well tool according to claim 10 wherein the packing means includesa cup-type upper packer element engageable with the well bore to holdpressure from above, and a cup-type lower packer element engageable withthe well bore to hold pressure from below.

17. A well tool according to claim 16 wherein the fluid pressure meansincludes a fluid chamber defined by formations associated with the bodyand formations associated with the expander including a wall elementmovable with the expander and constituting a movable wall of thechamber.

18. A well tool accordng to claim 17 wherein the upper and lower packerelements are both positioned on the body at a portion thereof on oneside of the fluid chamber, whereby the exterior of the chamber isexposed to a part of the well on one side of the packer elements, andfurther comprising passage means through the tool body and communicatingthe interior of the chamber with the part of the well bore on theopposite side of at least one of the packer elements.

19. A well tool comprising a body adapted to be lowered into a wellconduit, a cup-type upper packer element on the body for sealing theannular space between the body and the well conduit against passage ofwell fluids in a downward direction therethrough, a cup-type lowerpacker element on the body for sealing the annular space between thebody and the well conduitagainst the passage of fluid upwardlytherethrough, an expander having downwardly and inwardly inclinedsurfaces and mounted on the body for movement longitudinally of thebody, a first abutment on the body engageable with the expander torestrict the extent of movement of the expander upwardly along the body,slip means including slip elements having inclined surfacescomplementary to and engageable by the expander inclined surfaces, theslip means being mounted on the body below the expander for movementlongitudinally and laterally of the body and positioned to be engaged bythe expander and to be moved relatively therealong thereby selectivelyto be forced outwardly into anchoring engagement with the well conduit,a second abutment on the body engageable with the slip means to restrictthe extent of movement of the slip means downwardly along the body,friction drag means associated with the expander and engageable with thewell conduit to impede movement of the expander through the well bore,friction drag means associated with the slip means and engageable withthe well bore to impede movement of the slip means through the wellconduit, fluid pressure means coacting between the body and expander andoperable upon pressure conditions in the well tending to push the bodyin an upward direction in the well for forcing the expander toward theslip means to force the slips into anchoring engagement with the wellbore, the fluid pressure means including a fluid chamber of variablevolume defined by formations on the body and formations associated withthe expander including a portion constituting a moving wall of thechamber, the exterior of the chamber communicating with a part of thewell on one side of the lower packer element and the interior of thechamber communicating with a part of the well on the opposite side ofthe lower packing element form the first part, and control means movableon the body for engagement in a first position with the body and slipmeans to prevent movement of the slip means relative to the body and forengagement in a second position with the body and expander to preventmovement of the expander relative to the body and for disengagement in athird position from the body, slip means and expander and permit theslip means to become engaged with the conduit.

20. A well tool according to claim 19 wherein the upper and lower packerelements are both mounted on the body in positions above the fluidchamber, whereby the exterior of the chamber communicates with the partof the well below the lower packer, and further comprising passage meanscommunicating the interior of the fluid chamber with a part of the wellabove the lower packer element.

21. A well tool according to claim 19 further comprising a passagethrough the body and communicating parts of the well above and below theupper and lower packing elements with each other, and valve means in thepassage for selectively closing off the passage to prevent passage ofWell fluids between the said parts through the passage.

22. A well tool according claim 19 wherein the control means includes amember shiftable longitudinally of the body and elements coupled to themember and selectively engageabe in different positions of the memberrelative to the body with the body, expander, and slip means to maintainthe body, expander and slip means in selected positions relative to eachother.

23. A well tool according to claim 22 wherein the elements include acoupling member carried by the longitudinally shiftable member forrelative longitudinal movement thereon between limit positions andhaving portions selectively engageable with the body, expander and slipmeans.

24. A well tool according to claim 22 further comprising a passagethrough the body and communicating parts of the well above and below thepacker elements with each other, the passage including a bore in thetool body receiving the control member, and valve means in the passagefor selectively closing the passage to prevent passage of Well fluidstherethrough, the valve means including valve elements engageable withand shiftable by formations on the longitudinal control member.

References Cited UNITED STATES PATENTS Baker et al. 166-121 Baker et a1166120 X Evans 166121 X Chenoweth 166121 Young 166-420 Scott 16612lConrad 166133 X Chenoweth 166120 US. Cl. X.R.

$2,3 3? UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No,3 ,467 ,182 Dated September 16 1969 Inventor) J. W. Kisling III It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

T- Column 11, line 25, "zone" should be zones Column 12, line 46, "toenable relative movement of the slip means and expander" has beenomitted after "expander";

In the list of references, the date of U. S. patent No. 2,698,663 shouldbe "1/1955" (January, 1955) SIGNED AND SEALED MAY 121970 Attest:

Edward M. Fletchenlr. Attenting Officer WIILIAM L SOHUYLER. flomissionerof Paten

